HER2-overexpressing Cells Research Articles

Trastuzumab-Mediated Antibody-Dependent Cell-Mediated Cytotoxicity (ADCC) Enhances Natural Killer Cell Cytotoxicity in HER2-Overexpressing Ovarian Cancer.

Ovarian cancer is the deadliest gynecologic cancer. Although human epidermal growth factor receptor-2 (HER2) overexpression, a poor prognostic molecular marker in ovarian cancer, is found in almost 30% of ovarian cancer cases, there are no established therapies for HER2-overexpressing ovarian cancer. In this study, we investigated the efficacy of combined samfenet, a biosimilar compound of trastuzumab, and natural killer (NK) cells in preclinical model of HER2-overexpressing ovarian cancer. Firstly, we screened the HER2 expression in three ovarian cancer cell lines and eight ovarian cancer patient-derived tumor xenograft (PDTX) samples. Then, immunohistochemistry and silver in situ hybridization (SISH) were performed following clinical criteria. HER2-overexpressing cells exhibited the highest sensitivity to samfenet compared with low-HER2-expressing cells. In addition, the combination of samfenet with natural killer (NK) cells resulted in significantly enhanced sensitivity to HER2-overexpressing cells and showed a significant antitumor effect on PDTX mice compared with monotherapy. It is known that anti-HER2-humanized IgG1 monoclonal antibodies, including trastuzumab, induce antibody-dependent cellular cytotoxicity (ADCC). Consequently, the combination of samfenet with NK cells demonstrated NK cell-mediated ADCC, as confirmed using an in vitro NK cytotoxicity assay and in vivo antitumor efficacy. A transferase dUTP nick end labeling (TUNEL) assay using xenografted tumors further supported the ADCC effects based on the increase in the number of apoptotic cells in the combination group. Furthermore, high HER2 expression was associated with shorter progression-free survival and overall survival based on public mRNA expression data. In this study, we demonstrated that the combination of samfenet and NK cell therapy could be a promising treatment strategy for patients with HER2-overexpressing ovarian cancer, through ADCC effects. Therefore, this study supports a rationale for further clinical studies of the combination of samfenet and NK cells as a therapy for patients with HER2-overexpressing ovarian cancer.

Expression Profiling Identified TRPM7 and HER2 as Potential Targets for the Combined Treatment of Cancer Cells.

TRPM7 is a divalent cation-permeable channel that is highly active in cancer cells. The pharmacological inhibitors of TRPM7 have been shown to suppress the proliferation of tumor cells, highlighting TRPM7 as a new anticancer drug target. However, the potential benefit of combining TRPM7 inhibitors with conventional anticancer therapies remains unexplored. Here, we used genome-wide transcriptome profiling of human leukemia HAP1 cells to examine cellular responses caused by the application of NS8593, the potent inhibitor of the TRPM7 channel, in comparison with two independent knockout mutations in the TRPM7 gene introduced by the CRISPR/Cas9 approach. This analysis revealed that TRPM7 regulates the expression levels of several transcripts, including HER2 (ERBB2). Consequently, we examined the TRPM7/HER2 axis in several non-hematopoietic cells to show that TRPM7 affects the expression of HER2 protein in a Zn2+-dependent fashion. Moreover, we found that co-administration of pharmacological inhibitors of HER2 and TRPM7 elicited a synergistic antiproliferative effect on HER2-overexpressing SKBR3 cells but not on HER2-deficient MDA-MB-231 breast cancer cells. Hence, our study proposes a new combinatorial strategy for treating HER2-positive breast cancer cells.

Molecular and Clinicopathologic Characterization of HER2-overexpressed Squamous Cell Carcinoma of the Cervix.

HER2 amplification in cervical cancer has been associated with worse clinical prognosis and a potential favorable response to HER2 inhibitors. Immunohistochemistry for the HER2 receptor is a universally accepted surrogate test for HER2 amplification, but no standardized scoring system currently exists for cervical carcinomas. In this study, we investigated HER2 overexpression in cervical squamous cell carcinoma and correlated it with HER2 amplification using fluorescence in situ hybridization (FISH) and molecular methods. Seventy-two cases of human papillomavirus-associated cervical cancer were retrospectively reviewed, and at least 2 representative tumor sections were stained for HER2. HER2 scoring was performed using the 2018 American Society of Clinical Oncology/College of American Pathologist breast cancer criteria, and cases with equivocal (2+) to positive (3+) expression were analyzed for HER2 amplification using FISH and next-generation sequencing. The average patient age was 50yrs (range: 27-85yr), with most patients being African American (73.6%) and diagnosed at FIGO stage I (65.3%). Nineteen (26.4%) had equivocal HER2 expression and 4 (5.5%) showed positive expression. Three of the 4 cases with positive expression had enough tumors for FISH, and all 3 were amplified. Three cases with equivocal expression showed HER2 polysomy on FISH, and none showed HER2 amplification. Late clinical stage, high tumor grade, and regional lymph node metastasis were significantly correlated with HER2 overexpression and HER2 amplification. Next-generation sequencing of the 3 HER2-amplified tumors showed amplification of various genes, including CD274, JAK2, BIRC3, and ERBB2, and a PIK3CA missense mutation. In summary, HER2 immunohistochemistry is a reliable predictive marker of HER2 amplification in cervical cancer.

Supramolecular Bioconjugation Strategy for Antibody-Targeted Delivery of siRNA.

RNA interference is a widely used biological process by which double-stranded RNA induces sequence-specific gene silencing by targeting mRNA for degradation. However, the physicochemical properties of siRNAs make their delivery extremely challenging, thus limiting their bioavailability at the target site. In this context, we developed a versatile and selective siRNA delivery system of a trastuzumab-conjugated nanocarrier. These immunoconjugates consist of the assembly by electrostatic interactions of an oligonucleotide-modified antibody with a cationic micelle for the targeted delivery of siRNA in HER2-overexpressing cancer cells. Results show that, when associated with the corresponding siRNA at the appropriate N/P ratio, our supramolecular assembly was able to efficiently induce luciferase and PLK-1 gene silencing in a cell-selective manner in vitro.

Potential Advantages of Idarubicin-Loaded Trastuzumab-Coated Liposomes for Combating Head and Neck Squamous Cancer Cells.

Head and neck squamous cell carcinoma (HNSCC) with a high mortality rate is among the most common types of cancer in the world. Human epidermal growth factor receptor 2 (HER2) is expressed higher than normal level in the most HNSCC tumors, making them resistant to chemotherapy and radiotherapy. Therefore, HER2 has been introduced as a suitable target for anticancer drugs. The aim of this study is to examine the efficacy of a treatment protocol involving targeted delivery of idarubicin encapsulated in trastuzumab-decorated liposomes to HNSCC cells. In the current experimental study, efficacies of idarubicin, prepared liposomal idarubicin, and constructed immunoliposomal idarubicin (trastuzumab-decorated) were investigated in killing HN5 cells, a HER2- overexpressing HNSCC-originating cell line. Liposomal content of idarubicin and trastuzumab were qualified by UVVisible spectroscopy and preparations were characterized for shape and size by atomic force microscopy (AFM) and dynamic light scattering (DLS). To clarify role of the missing parts of the available crystal structure (PDB ID: 1n8z) within trastuzumab-HER2 interactions, we used a 40 ns molecular dynamic simulation approach. Based on the obtained results, liposomal idarubicin showed higher toxicity of the encapsulated drug on HN5 cells compared to the traditional free drug formulations. The immunoliposomal form of idarubicin was more effective than the liposomal formulation, in killing of HN5 cells. In addition, simulation of interactions between trastuzumab and HER2 revealed that the missing parts (in the crystal structure) of HER2 have critical interaction with trastuzumab, through salt-bridges and hydrogen bonds. It seems that the prepared immunoliposomes could attach more efficiently to HER2 overexpressing cells, which consequently leads to increasing cellular uptake of idarubicin through a receptor-mediated endocytosis mechanism. Moreover, simulation of the interaction between HER2 and trastuzumab suggested considerable possibilities for increasing trastuzumab affinity to HER2.

Enhanced anti-tumor effects by combination of tucatinib and radiation in HER2-overexpressing human cancer cell lines

BackgroundTucatinib (TUC), a HER2-directed tyrosine kinase inhibitor, is the first targeted drug demonstrating intracranial efficacy and significantly prolonged survival in metastatic HER2-positive breast cancer (BC) patients with brain metastases. Current treatments for brain metastases often include radiotherapy, but little is known about the effects of combination treatment with TUC. Therefore, we examined the combined effects of irradiation and TUC in human HER2-overexpressing BC, non-small cell lung cancer (NSCLC), and colorectal cancer (CRC) cell lines. For the latter two, a standard therapy successfully targeting HER2 is yet to be established.MethodsNine HER2-overexpressing (BC: BT474, ZR7530, HCC1954; CRC: LS411N, DLD1, COLO201; NSCLC: DV90, NCI-H1781) and three control cell lines (BC: MCF7, HCC38; NSCLC: NCI-H2030) were examined. WST-1 assay (metabolic activity), BrdU ELISA (proliferation), γH2AX assay (DNA double-strand breaks (DSB), Annexin V assay (apoptosis), and clonogenic assay (clonogenicity) were performed after treatment with TUC and/or irradiation (IR). The relevance of the treatment sequence was analyzed exemplarily.ResultsIn BC, combinatorial treatment with TUC and IR significantly decreased metabolic activity, cell proliferation, clonogenicity and enhanced apoptotis compared to IR alone, whereby cell line-specific differences occurred. In the PI3KCA-mutated HCC1954 cell line, addition of alpelisib (ALP) further decreased clonogenicity. TUC delayed the repair of IR-induced DNA damage but did not induce DSB itself. Investigation of treatment sequence indicated a benefit of IR before TUC versus IR after TUC. Also in CRC and NSCLC, the combination led to a stronger inhibition of metabolic activity, proliferation, and clonogenic survival (only in NSCLC) than IR alone, whereby about 10-fold higher concentrations of TUC had to be applied than in BC to induce significant changes.ConclusionOur data indicate that combination of TUC and IR could be more effective than single treatment strategies for BC. Thereby, treatment sequence seems to be an important factor. The lower sensitivity to TUC in NSCLC and particularly in CRC (compared to BC) implicates, that tumor promotion there might be less HER2-related. Combination with inhibitors of other driver mutations may aid in overcoming partial TUC resistance. These findings are of high relevance to improve long-time prognosis especially in brain-metastasized situations given the intracranial activity of TUC.

Population pharmacokinetics of trastuzumab deruxtecan (T-DXd) in subjects with HER2-mutant and HER2-overexpressing non-small cell lung cancer (NSCLC).

e20537 Background: T-DXd is a novel human epidermal growth factor receptor 2 (HER2) targeting antibody drug conjugate, approved globally at the dose of 5.4 mg/kg in HER2-positive or HER2-low breast cancer (BC) and HER2-mutant (HER2m) NSCLC1,2. The aim of the analysis was to characterize the populaton pharmacokinetics (PopPK) of T-DXd and its released payload, deruxtecan (DXd), in HER2m or HER2-overexpressing (HER2-OE) NSCLC subjects using data across tumor types (BC, NSCLC and others) from 12 Phase 1 to 3 studies with T-DXd doses ranging from 0.8-8.0 mg/kg. Methods: Analysis wasperformed using nonlinear mixed-effects modeling methods in NONMEM (version 7.4.3), similar to the previous analysis in HER2-positive BC1. Covariate effects were explored on the PK parameters of T-DXd and DXd. Results: Analysis included data across 1822 subjects, including 346, 1128, and 348 subjects with NSCLC, BC, and other cancers, respectively. The PK of T-DXd and DXd were adequately described by a PopPK model, judging by standard model diagnostics3. Covariate effects on T-DXd and DXd steady-state area under the concentration-time curve (AUC) were not clinically meaningful (within 0.8 to 1.25 AUC ratio interval for tested covariate level versus reference), except for subjects with high body weight (e.g., 90 kg; 95th percentile) showing a 31% and 37% higher T-DXd and DXd AUC, respectively, relative to typical subject with 58 kg body weight (median).The T-DXd and DXd AUC were also similar across subjects with BC, HER2m or HER2-OE NSCLC, with the same T-DXd dose. T-DXd and DXd AUC in NSCLC subjects were similar across subjects with mild hepatic or mild or moderate renal impairment (vs. normal counterparts), region (Asia, North America, Europe, and rest of the world), and race-country (Asian-Japan, Asian-Non-Japan, and Non-Asian) groups. Conclusions: T-DXd and DXd exposures were similar across subjects with BC and HER2m or HER2-OE NSCLC, as well as across hepatic function, renal function, region, and race-country groups within NSCLC supporting the use of 5.4 mg/kg dose (approved dose in BC) in HER2m or HER2-OE NSCLC from PK perspective. Reference: Enhertu [package insert]. Basking Ridge, NJ: Daiichi Sankyo, Inc.; 2022. Enhertu [summary of product characteristics]. Daiichi Sankyo Europe GmbH, Munich; 2022 Yin O et al. Clin Pharmacol Ther. 2021;109(5):1314-1325. Clinical trial information: NCT04644237 , NCT03505710 .

Site-selective antibody-lipid conjugates for surface functionalization of red blood cells and targeted drug delivery

Displaying antibodies on carrier surfaces facilitates precise targeting and delivery of drugs to diseased cells. Here, we report the synthesis of antibody-lipid conjugates (ALCs) through site-selective acetylation of Lys 248 in human Immunoglobulin G (IgG) and the development of antibody-functionalized red blood cells (immunoRBC) for targeted drug delivery. ImmunoRBC with the HER2-selective antibody trastuzumab displayed on the surface (called Tras-RBC) was constructed following a three-step procedure. First, a peptide-guided, proximity-induced reaction transferred an azidoacetyl group to the ε-amino group of Lys 248 in the Fc domain. Second, the azide-modified IgG was subsequently conjugated with dibenzocyclooctyne (DBCO)-functionalized lipids via strain-promoted azide–alkyne cycloaddition (SPAAC) to result in ALCs. Third, the lipid portion of ALCs was then inserted into the cell membranes, and IgGs were displayed on red blood cells (RBCs) to construct immunoRBCs. We then loaded Tras-RBC with a photosensitizer (PS), Zinc phthalocyanine (ZnPc), to selectively target HER2-overexpressing cells, release ZnPc into cancer cells following photolysis, and induce photodynamic cytotoxicity in the cancer cells. This work showcases assembling immunoRBCs following site-selective lipid conjugation on therapeutic antibodies and the targeted introduction of PS into cancer cells. This method could apply to the surface functionalization of other membrane-bound vesicles or lipid nanoparticles for antibody-directed drug delivery.

Augmented antitumor immune responses of HER2-targeted pyroptotic induction by long-lasting recombinant immunopyroptotins

Pyroptosis is a well-documented form of programmed cell death caused by the gasdermin-driven perforation of cell membranes. Selective induction of pyroptosis in tumor cells represents a promising antitumor strategy to enhance the efficacy of immunotherapy. In this study, we established a recombinant protein-based immunopyroptotin strategy that led to the intratumoral induction of pyroptosis for HER2-directed therapy. Long-lasting immunopyroptotins were constructed by sequentially fusing the humanized anti-HER2 single-chain antibody P1h3, albumin-binding peptide (ABD035 or dAb7h8), cathepsin B-cleavable peptide B2, endosome-disruptive peptide E5C3, and active pyroptotic effector gasdermin D-N fragment (GN). After purification, we evaluated the cytotoxicity and antitumor immune responses primarily induced by the immunopyroptotins in HER2-overexpressing breast cancer cells. The resulting ABD035-immunoGN and dAb7h8-immunoGN showed improved in vitro cytotoxicity in HER2-overexpressing cancer cells compared with that in the immunotBid that we previously generated to induce tumor cell apoptosis. The binding of long-lasting immunopyroptotins to albumin increased the half-life by approximately 7-fold in nude mice. The enhanced antitumor efficacy of long-lasting immunopyroptotins was confirmed in both N87 tumor-bearing T cell-deficient mice and 4T1-hHER2 bilateral tumor-bearing immunocompetent mice. Immunopyroptotin treatment elicited systemic antitumor immune responses involving CD8+ T cells and mature dendritic cells and upregulated the expression of proinflammatory cytokines, leading to sustained remission of non-injected distant tumors. This study extends the repertoire of antibody-based therapeutics through the tumor-targeted delivery of a constitutively active pore-forming gasdermin-N fragment, which shows great potential for pyroptosis-based antitumor therapy.

Efficacy and delivery strategies of the dual Rac/Cdc42 inhibitor MBQ-167 in HER2 overexpressing breast cancer

Trastuzumab and trastuzumab-based treatments are the standard of care for breast cancer patients who overexpress the human epidermal growth factor receptor 2 (HER2). However, patients often develop resistance to trastuzumab via signaling from alternative growth factor receptors that converge to activate guanine nucleotide exchange factors (GEFs) that in turn activate the Rho GTPases Rac and Cdc42. Since Rac and Cdc42 have been implicated in high tumor grade and therapy resistance, inhibiting the activity of Rac and Cdc42 is a rational strategy to overcome HER2-targeted therapy resistance. Therefore, our group developed MBQ-167, a dual Rac/Cdc42 inhibitor with IC50s of 103 nM and 78 nM for Rac and Cdc42, respectively, which is highly effective in reducing cell and tumor growth and metastasis in breast cancer cell and mouse models. Herein, we created a trastuzumab resistant variant of the SKBR3 HER2 positive breast cancer cell line and show that Rac activation is a central mechanism in trastuzumab resistance. Next, we tested the potential of targeting MBQ-167 to HER2 overexpressing trastuzumab-resistant cell lines in vitro, and show that MBQ-167, but not trastuzumab, reduces cell viability and induces apoptosis. When MBQ-167 was targeted to mammary fatpad tumors established from HER2 overexpressing cells via immunoliposomes functionalized with trastuzumab, MBQ-167 and MBQ-167-loaded liposomes show equal efficacy in reducing the viability of trastuzumab-resistant cells, inhibiting tumor growth in mouse xenografts, and reducing metastasis to lungs and liver. This study demonstrates the efficacy of MBQ-167 as an alternative therapeutic in HER2 overexpressing cancers, delivered either in free form or in liposomes.

Chimeric nanobody-decorated liposomes by self-assembly.

Liposomes as drug vehicles have advantages, such as payload protection, tunable carrying capacity and improved biodistribution. However, due to the dysfunction of targeting moieties and payload loss during preparation, immunoliposomes have yet to be favoured in commercial manufacturing. Here we report a chemical modification-free biophysical approach for producing immunoliposomes in one step through the self-assembly of a chimeric nanobody (cNB) into liposome bilayers. cNB consists of a nanobody against human epidermal growth factor receptor 2 (HER2), a flexible peptide linker and a hydrophobic single transmembrane domain. We determined that 64% of therapeutic compounds can be encapsulated into 100-nm liposomes, and up to 2,500 cNBs can be anchored on liposomal membranes without steric hindrance under facile conditions. Subsequently, we demonstrate that drug-loaded immunoliposomes increase cytotoxicity on HER2-overexpressing cancer cell lines by 10- to 20-fold, inhibit the growth of xenograft tumours by 3.4-fold and improve survival by more than twofold.

Evaluation of 177Lu-Labeled Pertuzumab F(ab')2 Fragments for HER2-Positive Cancer Targeting: A Comparative In Vitro and In Vivo Study.

Background: Radiolabeled antibody fragments present a promising opportunity as theranostic agents, offering distinct advantages over whole antibodies. In this study, the authors investigate the potential of [177Lu]Lu-DTPA-F(ab')2-pertuzumab as a theranostic agent for precise targeting of human epidermal growth factor receptor 2 (HER2)-positive cancers. Additionally, the authors aim to quantitatively assess the binding synergism in the presence of cold trastuzumab. Materials and Methods: F(ab')2-pertuzumab was prepared by pepsin digestion and conjugated with a bifunctional chelator. The immunoconjugate was radiolabeled with 177Lu and characterized by chromatography techniques. Binding parameters (affinity, specificity, and immunoreactivity) and cellular binding enhancement studies were evaluated in HER2-overexpressing and triple-negative cell lines. The in vivo enhancement in tumor uptake of the radiolabeled immunoformulation was assessed in severe combined immunodeficient (SCID) mice bearing tumors, both in the presence and absence of unlabeled trastuzumab. Results: The formulation of [177Lu]Lu-DTPA-F(ab')2-pertuzumab could be prepared in high yields and with consistent radiochemical purity, ensuring reproducibility. Comprehensive in vitro and in vivo evaluation studies confirmed high specificity and immunoreactivity of the formulation toward HER2 receptors. Binding synergism of radiolabeled pertuzumab fragments in the presence of trastuzumab to HER2 receptors was observed. Conclusions: The radioformulation of [177Lu]Lu-DTPA-F(ab')2-pertuzumab holds great promise as a targeted approach for addressing HER2-positive cancers. A potentially effective strategy to amplify therapeutic efficacy involves dual epitope targeting by combining radiolabeled pertuzumab with cold trastuzumab.

The diagnostic value of 68Ga-NOTA-MAL-Cys-MZHER2:342 PET/CT imaging for HER2-positive lung adenocarcinoma.

The human epidermal growth factor receptor 2 gene (HER2) has been identified as a potential therapeutic target in lung adenocarcinoma (LUAD). Non-invasive positron emission tomography (PET) imaging provides a reliable strategy for in vivo determination of HER2 expression through whole-body detection of abnormalities. The PET tracer 68Ga-NOTA-MAL-Cys-MZHER2:342 has shown promising results for HER2-positive breast and gastric cancers. This study aims to evaluate the performance of 68Ga-NOTA-MAL-Cys-MZHER2:342 in vitro and in vivo models and in clinical patients with HER2-positive LUAD. NOTA-MAL-Cys-MZHER2:342 was synthesized and labeled with 68Ga. Cell uptake, cell binding ability, and stability studies of 68Ga-NOTA-MAL-Cys-MZHER2:342 were assessed both in the Calu-3 lung cancer (LC) cell line and normal mice. In vivo assessment in tumor-bearing mice was conducted using microPET imaging and biodistribution experiments. Additionally, preliminary PET/CT imaging analysis was performed on HER2-positive LC patients. 68Ga-NOTA-MAL-Cys-MZHER2:342 was prepared with a radiochemical purity (RCP) exceeding 95%. The tracer demonstrated high cell uptake in HER2-overexpressing Calu-3 cells, with an IC50 of 158.9, an adequate 1.73 nM. Good stability was exhibited both in vitro and in vivo. MicroPET imaging of Calu-3-bearing mice revealed high tumor uptake and notable tumor-to-background ratios. Positive outcomes were also observed in two HER2-positive LUAD patients. 68Ga-NOTA-MAL-Cys-MZHER2:342 demonstrated satisfactory stability, sensitivity, and specificity. These findings suggest that 68Ga-NOTA-MAL-Cys-MZHER2:342 PET/CT imaging provides a novel tool for non-invasive visual assessment of HER2 expression in LUAD patients.

Targosomes: Anti-HER2 PLGA nanocarriers for bioimaging, chemotherapy and local photothermal treatment of tumors and remote metastases

Developing combined cancer therapy strategies is of utmost importance as it can enhance treatment efficacy, overcome drug resistance, and ultimately improve patient outcomes by targeting multiple pathways and mechanisms involved in cancer growth and progression. Specifically, the potential of developing a combination chemo&photothermal therapy using targeted polymer nanoparticles as nanocarriers offers a promising approach for synergistic cancer treatment by combining the benefits of both therapies, such as targeted drug delivery and localized hyperthermia. Here, we report the first targeted anti-HER2 PLGA nanocarriers, called targosomes, that simultaneously possess photothermal, chemotherapeutic and diagnostic properties using only molecular payloads. Biocompatible poly(lactic-co-glycolic acid), PLGA, nanoparticles were loaded with photosensitizer phthalocyanine, diagnostic dye Nile Blue, and chemotherapeutic drug irinotecan, which was chosen as a result of screening a panel of theragnostic nanoparticles. The targeted delivery to cell surface oncomarker HER2 was ensured by nanoparticle modification with the anti-HER2 monoclonal antibody, trastuzumab, using the one-pot synthesis method without chemical conjugation. The irradiation tests revealed prominent photothermal properties of nanoparticles, namely heating by 35 °C in 10 min. Nanoparticles exhibited a 7-fold increase in binding and nearly an 18-fold increase in cytotoxicity for HER2-overexpressing cells compared to cells lacking HER2 expression. This enhancement of cytotoxicity was further amplified by >20-fold under NIR light irradiation. In vivo studies proved the efficacy of nanoparticles for bioimaging of primary tumor and metastasis sites and demonstrated 93% tumor growth inhibition, making these nanoparticles excellent candidates for translation into theragnostic applications.

In Vivo and In Vitro Efficacy of Trastuzumab Deruxtecan in Uterine Serous Carcinoma.

Uterine serous carcinoma (USC) is a rare, biologically aggressive variant of endometrial cancer with a high recurrence rate and poor prognosis. HER2 overexpression (3+ positivity) by IHC and/or FISH ERBB2 gene amplification is detected in approximately one-third of patients with USC. Clinical trials incorporating trastuzumab with standard chemotherapy have recently demonstrated improved progression-free and overall survival in advanced-stage or recurrent USC that overexpresses HER2. However, a large number of patients with USC eventually developed resistance to trastuzumab. Trastuzumab deruxtecan (T-DXd) is a novel HER2-directed antibody-drug conjugate with a topoisomerase I inhibitor payload recently approved by the Food and Drug Administration (FDA) for multiple tumor indications. Here, we investigated the in vitro and in vivo efficacy of T-DXd in primary USC cell lines and xenografts with different HER2 expression. T-DXd-induced cell growth suppression in HER2-overexpressing cell lines in vitro, increased early and late apoptosis as assessed by annexin and propidium iodide staining, and, similarly to trastuzumab, T-DXd-induced significant antibody-dependent cellular cytotoxicity in the presence of peripheral blood lymphocytes. While negligible activity was detected against USC cell lines with low HER2 expression, T-DXd demonstrated significant bystander killing against USC tumors with low/negligible HER2 when such cells were admixed with HER2 3+ tumor cells in vitro. T-DXd showed tumor growth suppression in in vivo USC PDX models that overexpress HER2 at 3+ levels, prolonging survival when compared with controls, with minimal toxicity. Future clinical trials are warranted in patients with USC failing trastuzumab treatment.

A phase 1, open-label, first-in-human study of TAS2940 in patients with advanced solid tumors.

TPS3165 Background: Aberrant expression and signaling of the ERBB family of receptor tyrosine kinases, including epidermal growth factor receptor (EGFR) and human epidermal growth factor receptor 2 (HER2), has a role in the pathogenesis of solid tumors such as breast cancer (BC), non–small cell lung cancer (NSCLC), and glioblastoma (GBM). Although therapies that target HER2 are effective in early and advanced HER2-overexpressing BC, many patients develop resistance despite tumor dependence on HER2 at the time of progression. Approximately 4% of patients with NSCLC have HER2 mutations, mostly presenting as exon 20 insertions (ex20ins); however, approved HER2/EGFR tyrosine kinase inhibitors (TKIs) have limited efficacy in patients with NSCLC and HER2 ex20ins. Many patients with NSCLC or BC develop brain metastases, and EGFR alterations, including EGFRvIII mutations, are common in GBM. There is therefore a need for a brain-penetrable TKI with activity against tumors harboring HER2/EGFR alterations. TAS2940 is a potent, selective, and orally bioavailable pan-ERBB inhibitor that has shown promising preclinical efficacy against cancers with a variety of HER2/EGFR mutations and amplifications. Further, TAS2940 inhibited tumor growth and induced tumor regression in a dose-dependent manner in nude mice intracranially implanted with NCI-N87, a HER2-overexpressing human gastric cancer cell line. Methods: TAS2940-101 (NCT04982926) is an open-label, phase 1, first-in-human trial to evaluate the safety, tolerability, pharmacokinetics (PK), and preliminary antitumor activity of TAS2940 in patients with advanced solid tumors and HER2/ EGFR aberrations. Eligible patients are aged ≥18 years, have non-measurable (Part 1) or measurable (Part 1 and 2) disease per RECIST 1.1 or RANO criteria, ECOG performance status 0/1, and adequate organ function. Patients with non-stable brain metastases are excluded. Part 1 (dose escalation) will use a Bayesian optimal interval design with a starting dose of 15 mg/kg orally QD (planned dose levels: 15, 30, 60, 120, 240 and 480 mg). Once the recommended phase 2 dose is determined, Part 2 (dose expansion) will enroll patients with NSCLC (Cohort A), HER2+ BC (Cohort B), recurrent/refractory GBM (Cohort C), or other solid tumors with EGFR/ HER2 aberrations (Cohort D). The primary objectives are the maximum tolerated dose of TAS2940 in Part 1 and antitumor activity in Part 2. Secondary objectives include antitumor activity in Part 1. The safety and PK profile of TAS2940 will be assessed in both parts. Approximately 142 patients will be enrolled, comprising ~42 in Part 1 and ~100 in Part 2. As of January 24, 2023, 15 patients have been enrolled. No dose-limiting toxicities have been reported with dose escalation up to 240 mg QD. Recruitment is ongoing. Clinical trial information: NCT04982926 .

Epstein-Barr virus immediate-early protein Zta mediates the proliferation and migration of HER2-overexpressing cancer cells.

Epstein-Barr virus immediate-early protein Zta plays an active role in altering cellular gene expression, which may be fundamentally linked to the viral life cycle, cell cycle, cell growth, and differentiation. HER2 is associated with a wide variety of human cancers, and its knockdown significantly reverses the malignant features of HER2-positive cancers. The aim of this study was to investigate the potential role of Zta in regulating HER2 expression and phenotype changes of MDA-MB-453 cells. Our results indicate that ectopic expression of Zta resulted in downregulation of the HER2 protein in cancer cells (MDA-MB-453, SKBR-3, BT474, and SKOV-3). The Zta protein significantly decreased HER2 mRNA and protein expression in MDA-MB-453 cells in a dose-dependent manner. Mechanistically, Zta recognized and targeted the promoter of HER2 gene, reducing the transcriptional activity of the HER2 gene. Zta induced G0/G1 arrest of MDA-MB-453 cells, inhibiting their proliferation and migration activity. These data suggest that Zta may act as a transforming suppressor of the HER2 gene.

Abstract LB091: Design, characterization and preclinical validation of a combinatorial CAR-based immunotherapy against colorectal cancer with HER2 amplification

Abstract Adoptive immunotherapy based on chimeric antigen receptor (CAR)-T cells has led to successful treatment of some hematological malignancies, but it remains extremely challenging for solid tumors, mostly because of “on-target off-tumor” toxicity, as observed in the case of anti-HER2 CAR-T treatment of colorectal cancer (CRC) with HER2 amplification. To enable adoptive immunotherapy against HER2-amplified CRC, we therefore considered a combinatorial strategy based on the synNotch-based artificial regulatory network. A synthetic Notch receptor was employed in which the extracellular domain is an anti-HER2 scFv and the intracellular domain contains the GAL4-VP64 artificial transcription factor. Engagement of the anti-HER2 domain by target cells drives GAL4-VP64 cleavage and translocation to the nucleus, where it drives expression of a CAR under a GAL4-responsive promoter. In this way, only cells co-expressing both HER2 and the CAR target are killed. As a CRC-specific CAR target we selected CEA, product of the CEACAM5 gene. CEA expression is restricted to the digestive tract and is increased in cancer. For the generation of HER2-synNotch CEA-CAR effectors, we chose the natural killer cell line NK-92 and transduced it with two lentiviral vectors, encoding respectively the HER2 synNotch and the second-generation anti-CEA CAR with CD28 costimulatory domain. Transduced cells were repeatedly sorted in the ON and OFF state to select those with the best CAR induction after synNotch engagement; cloning of sorted cells led to identification of an optimally responsive clone (clone 5F), showing no basal CEA-CAR expression and massive induction in the presence of HER2-overexpressing cancer cells. In vitro, the 5F clone displayed selective cytotoxicity against HER2++/CEA++ CRC cells, with minimal killing activity against HER2++/CEA- breast cancer cells, or against CRC cells expressing CEA but without HER2 amplification. In vitro 3D models highlighted better recruitment and infiltration by NK-92 clone 5F respect to NK-92 WT cells, only of HER2++ organoids. In vivo, the clone 5F significantly impaired tumor growth in two different HER2++ CRC models. The observed selective efficacy both in vitro and in vivo of the HER2-synNotch/CEA-CAR approach opens a perspective for possible clinical applications in cases of HER2-amplified CRC displaying primary or secondary resistance to HER2/EGFR blockade. Citation Format: Marco Cortese, Erica Torchiaro, Federica Invrea, Consalvo Petti, Alice D'Andrea, Sabrina Arena, Enzo Medico. Design, characterization and preclinical validation of a combinatorial CAR-based immunotherapy against colorectal cancer with HER2 amplification [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 2 (Clinical Trials and Late-Breaking Research); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(8_Suppl):Abstract nr LB091.

Abstract 2622: Targeting Rac/Cdc42 GTPases to overcome HER2-targeted therapy resistance

Abstract Breast cancer is the most common cancer in women. Breast cancer is categorized by the overexpression (or lack thereof) of estrogen receptors (ER+/-), progesterone receptors (PR+/-) or human epidermal growth factor 2 receptors (HER2+/-). Specifically, HER2+ breast cancer is one of the most aggressive subtypes, comprising ~20% of all cases. Overexpression of the HER2 receptor leads to active downstream signaling that results in cell proliferation and metastasis. Clinically, this problem has been tackled by targeting the HER2 receptor with antibodies (e.g., Trastuzumab, Pertuzumab) and (or) tyrosine kinase inhibitors (TKIs; e.g., Lapatinib). However, patients may present with intrinsic or acquired resistance to these therapies. Molecular mechanisms of resistance to HER2 targeted therapy include activating mutations, alterations in downstream effectors, and compensation from other growth factor receptors. The active signaling sequelae from such mechanisms converge on the activation of guanine nucleotide exchange factors (GEFs) that regulate the GTPases Rac and Cdc42. These GTPases are critical for cell migration/invasion and have been correlated with poor prognosis in breast cancer patients. Therefore, targeting the activation of Rac/Cdc42 is a rational strategy to overcome HER2-targeted therapy resistance. Previously, we characterized the dual Rac/Cdc42 inhibitor MBQ-167 with IC50s of 103nM and 78nM for Rac and Cdc42, respectively. Our objective is to test MBQ-167 as an alternative to overcome HER2-targeted therapy resistance. To test the hypothesis that MBQ-167 will overcome HER2 therapy resistance, metastatic trastuzumab resistant HER2 overexpressing cells were treated with vehicle or individual or combined Trastuzumab and MBQ-167. Rac activity was determined by pulldown assays for active (GTP-bound) Rac, and viability was tested by MTT assays. Additionally, we measured apoptosis via caspase 3/7 activity and western blotted for the active signaling sequelae downstream of Rac. MBQ-167 reduced Rac activity and downstream signaling, as well as cell viability with a GI50 of 78nM after 72 hours, while caspase activity was increased after 24 hours of treatment. The results presented herein show the utility of the Rac/Cdc42 inhibitor MBQ-167 in overcoming HER2-targeted therapy resistance. Citation Format: Miciely Cristal Aponte Reyes, Luis E. Velazquez Vega, Suranganie Dharmawardhane. Targeting Rac/Cdc42 GTPases to overcome HER2-targeted therapy resistance [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 2622.

Abstract 6132: Impact of treatment with agents targeting different members of HER family, CDKs and downstream cell signaling molecules on growth and migration of stomach cancer cells

Abstract Stomach cancer ranks fifth and fourth for the incidence and mortality rate for cancer worldwide, respectively. In recent years, several inhibitors with specificity to one or more members of human epidermal growth factor receptor (HER) family have been approved for the treatment of patients with different cancer types. Of these, only the anti-HER2 monoclonal antibody (mAb) Herceptin/trastuzumab and the antibody-drug conjugate trastuzumab deruxtecan has been approved for the treatment of patients with stomach cancer. However, the duration of response may be short in many patients and with tumor heterogeneity being one contributing factor. In this study, we investigated the effect of various types of targeted agents on the growth in vitro of a panel of human stomach cancer cells (HSCCLs) and the impact of stomach cancer proliferation rate on the anti-tumor activities of these agents. Moreover, we investigated the cell surface expression of the HER family members, other biomarkers such as C-Met, Alk-7 and cancer stem cell makers CD44 and CD133 by flow cytometry and the effect various targeted agents on tumor migration using Incucyte. Of the 18 agents examined, the CDK 1/2/5/9 inhibitor dinaciclib was the most effective and inhibited the growth of all human HSCCLs at IC50 values between 1nM to 9nM. Of various HER inhibitors, the irreversible pan-HER family inhibitors (e.g., afatinib) were more effective than the reversible dual EGFR/HER2 TKI lapatinib and the EGFR specific TKI erlotinib in inhibiting the growth of HSCCLs. Interestingly, the HER-2 overexpressing cells lines NCI-N87 (Mean Fluorescence Intensity =596) was most sensitive to the HER inhibitors. Of agents targeting different downstream cell signaling molecules, dasatinib targeting Ab1/Src/C-Kit, trametinib targeting MERK1/2 and miransertib targeting AKT1/2/3 inhibited growth of majority of HSCCLs and with the IC50 values ranging from 2nM to 7uM. Interestingly, many of these agents were more effective in inhibiting the growth of HSCCLs when proliferating at slower rate. Of the agent examined, neratinib, afatinib, dinacicilib, dasatinib, stattic and miransertib also inhibited the migration of stomach cancer cells. Finally, treatment with a combination of afatinib with dinaciclib, capmatinib, dasatinib, stattic, ponatinib or miransertib resulted in synergistic and additive growth inhibition of stomach cancer cells. As stomach cancer cells are heterogenous in nature, our results support further research on the therapeutic potential of the CDK dinaciclib in combination with a pan-HER inhibitor in stomach cancer. Citation Format: Tina Al-Janaby, Narmin Nahi, Said A. Khelwatty, Alan Seddon, Izhar Bagwan, Helmout Modjtahedi. Impact of treatment with agents targeting different members of HER family, CDKs and downstream cell signaling molecules on growth and migration of stomach cancer cells. [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 6132.